Magenn

And an air Magnus balloon can easily scale, probably more than a kite. I easily realized cylindrical solar balloons until 800 m3, 10 m diameter and 20 m height Solar balloon jumping. The basis was open while the air Magnus balloon should be closed.

See also a 92 m blimp without internal structural framework.
https://www.ingenia.org.uk/Ingenia/Articles/40fced9b-394d-4c6f-a9a7-ed0b952023a8

Moreover the air mass in rotation would add some stability.

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An most of all - the build is really simple… just the outside skin and the rotating drive, pressurize it and add a small pump for leakage… and a onboard HAWT turbine for internal use…

Here is a similar concept to magnus wings. The wing it seems has a C_L in the range 4 to 6 at the moment (which is nuts large if anyone wondered).

A few notes and links-

  • Low Power to Weight is not made up by high Cl.

  • Comparison of high Cl should be made with wings with slats and flaps, like modern airliner wings.

https://www.quora.com/What-are-the-effects-of-slats-and-flaps-on-lift-curve

  • Comparison also with biplanes and large low-wing-loading wings.

  • For professional fire fighting, airplanes need to ferry long distances, wherever the fires are in a given year. A slow inefficient cruise is not favored.

  • Low noise is a definite FanWing advantage, but not for fire fighting.

  • Gyroscopic stability becomes an issue if the aircraft needs to roll fast.

  • Hopeful Monsters are loveable, but struggle to survive:

https://rationalwiki.org/wiki/Hopeful_monster

Magnus Effect of a sport ball-

Lift to weight is a metric you seem to put very highly, though our calculations show kite weight is only a big factor in the lower wind range due to gravity slowdown. Higher C_L might even alleviate gravity slowdown. I will agree that mass in general is a bad thing, as is additional motors and moving parts, as is high onboard power use.

Still magnus/fanwing remains an interesting option for AWE, if not the most probable route to success…

Apart from FanWing, and by being focused on AWES, such a comparison with air Magnus balloon would be relevant by taking account of both weight and ease of construction. An AWE rigid plane with (possibly fixed in the construction) slats and flaps is not easy to build but not impossible. Perhaps some soft kites could also obtain a high CL with means comparable to slats and flaps. I think about 4 lines power kites where it is possible to bend the trailing edge during flight, but not with a good result as the initial L/D ratio is already too low.
So for AWE air Magnus balloon is a possible high CL option.

Magnus can only develop high Cl at poor power-to-weight compared to a mass-equivalent power kite.

One way of visualizing the comparison would be to make a SS power kite of the same surface area and mass as the balloon fabric, with no flying motor-gen.

The math paints the same picture about power-to-weight. High Cl has traditionally only been essential for landing a large airplane on a shorter runway, when the plane is dropping and slowing anyway, bleeding off energy.

Let anyone do comparative testing for those who still have doubts.

There are many classic kite designs, “sticky” and soft, with multiple surfaces like a slatted flap wing; not the best flyers.

Magnus will be quite good wrt wildlife…

The First Order Wildlife Factor to AWE Tech is the looming Holocene Extinction. Magnus AWES is a poor engineering choice from that over-arching perspective.

Its plausible that a higher-performing architecture that kills more birds and bats directly could paradoxically save them better from the Holocene Extinction. Once again, the Power Kite seems to be in the Goldilocks zone between inferior design extremes.

Good point…

The Holocene extinction worried me. But now we are saved thanks to the Power Kite. Thanks @kitefreak to be farseeing enough to indicate the way of salvation of humanity and other species.

Pierre, You have not given much prior public notice of concern for extinction, but we are NOT saved yet.

It will take a heroic effort by AWE developers to make the difference. The power kite is far more than pretext for ridicule.

Good luck to anyone who still hopes Magenn can help. Its reasonable to keep the Magnus concept in testing for those who want better data.

@PierreB I hope you dont mind me quoting the data you posted elsewhere:

Blockquote My observations and my question concerns the power consumption of AWES based on Magnus effect but also the Sharp rotor as they scale.

To begin some informations:

  • The chapter 12 of the AWEbook 2018 mentions in page 290 that experiments with a small-scale system (Magnus rotor radius = 0.047 m and length = 0.45 m) the motor power consumption " is much larger than the power produced by the system due, among others, to the significant effect of frictions. For larger scale systems, frictions become less important compared to aerodynamic forces."

  • Omnidea’s curves on https://collegerama.tudelft.nl/Mediasite/Play/e51a679525fe491990de3a55a912f79d1d show that the motor power consumption is 1/3 or 1/4 the power produced by the system.

  • “Low C for the High Seas Flettner rotor power contribution on a route Brazil to UK Figure 1: One of the first rotor ships, the Buckau (left), and the present-day rotor ship E-Ship 1 (right) Source: wikipedia.org (accessed on 10 August 2012, right photo by Carschten). The Flettner rotor modeled here is 35 m tall and 5 m in diameter. Key to its aerodynamic performance are the lift, drag, and moment coefficients, respectively. They determine the lift force l , the drag force d , and the power pME that is needed to drive the rotor.The rotational speed ratio is set to α=3.5. The aerodynamical coefficients are set to cL=12.5, cD=0.2, and cM=0.2, respectively.”

So for Magnus large scale systems the power consumption ratio would be relatively lesser.

The numbers C_L = 12.5 and C_D = 0.2 seem very good and I would assume a best case scenario that could not be expected in real life without further R&D into building such wings.

From what I gather by reading stuff here and there putting in 1/3 or 1/4 of the energy is not uncommon for magnus effect.

I think much of this is due to skin friction, and we cannot expect this to reduce with scale, because, well, skin scales linearily with the projected area of the wing.

Furthermore, the problem for single tether AWE if getting the energy from the kite to the ground, assuming tether strength/mass/diameter to be the main limiting factors. Thinking this way, it doesnt really matter too much if you need to spend that energy locally on the wing.

If a C_D of 12 was realistic, a magnus wing with wingspan 10 m would replace a traditional wing (rigid wing of an airplane) with wingspan 22 meter (the aspect ratio being similar for the two). Though the magnus wing has a much lower glide number and is even more complex to build, I am not sure which is the better option now.

Now to add a few negative aspects og magnus: Because tether is your limiting design factor, you want the kite pull (and thus speed) to be constant. This is not easy to achieve. For magnus wings I cannot see an efficient way to control the power of the wing. You could change the rotational speed during a loop, but that induces further losses (breaking torque) and more weight for the increase in rotor motor power.

Of course you also need a quite hefty power generator for the rotor motors, causing further drag and mass penalty. The power generator probably would introduce a tail to the kite, as now the kite needs to be facing the wind (something that was not really important for just the manus wings)

Let me add, like you did, gyroscopic forces during a loop, along with no straightforward way to control roll and yaw… at least not in a millisecond feedback control sense.

Some of these issues (control issues in particular) would be mitigated by putting the magnus wings in a network, giving then more constant flying speed and reducing the need for power control.

Too good. However cM of 0.2 looks realistic, above all in regard to another coefficient indicated in the chapter 12.

This looks likely, but the high difference of power consumption has been measured for small cylinders ("…much larger than the power produced…") and larger balloons like Omnidea (about 1/3 or 1/4). Perhaps it is due to the relatively higher inertia mass for a larger balloon, I don’t know.

It looks like you envisage crosswind maneuvers for the Magnus balloon. But imho they don’t add so much power in regard to a not crosswind Magnus balloon: something like 2 times. And using two balloons could be easier in regard to the control concern. The more static the Magnus balloon, the better it is.

Why would it not generate heaps of power? even with a glide ratio of 2 you could see 4x force?

In crosswind maneuvers the power is not regular, and the average power is far below the peak power.

Is the wing power production itself irregular, or are you talking about gravity and cosine losses in general?

The second. Even Miles L Loyd mentioned (“Crosswind kite Power” http://homes.esat.kuleuven.be/~highwind/wp-content/uploads/2011/07/Loyd1980.pdf) these losses due to a not quite perpendicular swept area in regard to the wind direction. HAWT are not concerned as the air flow is perpendicular to the swept area.
And also variations of power likely add losses to losses.

I think I understand, but these variations are not intrinsic to the wing, rather the AWE rig architecture.

A magnus could be used in many architectures if fit for purpose; yoyo, drag, rotating, etc

As far as I’m concerned a wing is foremost described by the polar curves (C_L and C_D) along with more practical aspects such as maneuverability, depowerability, ease og build, power requirements, mass etc.

So I am still thinking we have mapped out the magnus wing quite well in our discussions, not missing any showstoppers. Next step would be more analysis, tests and eventually builds.

Tallak,

You keep leaving out (max) Area in how “a wing is foremost described”. A sufficiently large wing with a lower Cl can beat a smaller wing with higher Cl. “Mass” as in power-to-mass, should not be so far down your list.

These differing choices and ranking of key factors is why we select such different wings as most promising.